Do you want to enable/disable Back to Top button ? If so, here are simple instruction.
First of all, you can open WordPress Dashboard. Now you can click on SEOPress Options link. You can see this link in admin tool bar and it is also sub menu of Appearance menu.
Now you can click on MISC Options. Here you will see a toggle button for Back to Top. It use to enable/disable back to top icon of your website.
If you will turn it on, then Back to Top icon will be enabled on front end website.
Thanks and Enjoy !!